Semiautomatic pipe nipple threading machine



Dec. 16, 1952 JACOBSQN ETAL 2,621,346

SEMIAUTOMATIC PIPE NIPPLE THREADING MACHINE Filed Oct. 2?, 1948 4Sheets-Sheet l ww F 0 R M m.

l. D. JACOBSON ET'AL 2,621,346

SEMIAUTOMATIC PIPE NIPPLE THREADING MACHINE Filed Oct. 27, 1948 Dec. 16,1952 4 Sheets-Sheet 2 SN mm B mo VC wfimn mm m m m I m km 2 w Q i o A m73 PM 0 mm QM MN 5 M cm a 3 No RE 0 I mm NW @m H w a 2.

8 ICHAED F. #522 Dec. 16, 1952 D. JACOBSON EIAL 2,621,346

SEMIAUTOMATIC PIPE NIPPLE THREADING MACHINE Filed Oct. 27, 1948 4Sheets-Sheet 3 IN V EN TORS [E v//v D. JACOBS o/v QEICHARD F HER/E w WATTO/E/VZYS Patented Dec. 16, 1952 UNITED STATES ATENT OFFICESEMIAUTOMATIC PIPE NIPPLE THREADING MACHINE of Ohio Application October27, 1948, Serial No. 56,762

6 Claims. 1

This invention relates to threading machinery, particularly toproduction threading machinery adapted for threading short lengths ofpipe to form commercial pipe nipples.

Continued efforts over a great many years to increase the speed ofproduction of threaded pipe nipples, and consequently reduce the cost,have resulted in two basic types of machines which are employed in thetrade. One type is known as a hand machine, in that feeding, loading andcontrol of the machine carriage is done by the operator. The other typof machine is a full automatic that threads both ends of lengths of pipeto form the nipples. It is a feature of the present invention that incomparison with the prior machines an unexpected increase in production,under safer working conditions is provided, these advantages beingobtained by a novel combination and arrangement of machine elements thatcooperate to form. in the preferred embodiment, a relatively simple,semi-automatic hand-controlled device, although many features of theinvention may also be incorporated, with corresponding increase inproduction, in automatic machines. For example, one type of hand machinecommonly found in the trade employs a manually reciprocable carriagecarrying manuallyoperated chuck jaws or gripper for the nipples, and arotatable self-opening die head mounted in a fixed position on the bedin the machine. With prior machines of this type, the operator mustplace the nipple in the chuck jaws by placing one hand between therotating die head and the jaws (a dangerous position), and manipulate ahandwheel to open and close the jaws manually with the other hand. Hemust then move said other hand from the jaw controlling hand wheel to alever disposed on the carriage of the machine that permits him toadvance the carriage and start the threading operation. The dies aregenerally self-threading, and during the threading operation theoperator must retract the carriage and open the jaws of another unitdisposed on the same bed, which is supplied with nipples threaded at oneend. Thus, considerable manipulation is required between successivethreading operations, and a substantial amount of time is consumedthereby limiting the production of the machine.

By contrast, with a machine made according to this invention, means areprovided whereby the grippers on the carriage are automaticallyopenedand closed in response to the position of the carriage relative tothe threading die,

and a feeding and discharge arrangement is provided wherein a new blankor length of pipe is positioned in the gripper and the threaded blank isdischarged during the retraction of the carriage. Thus, loading of theblanks in position to be picked up during the next stroke of the carriagis effected under safe conditions during the threading operation, asopposed to the prior arrangement wherein the blank must be inserted bythe operator in the grippers just before the threading operation. Therelationship of the carriage-controlled grippers and theblank-supporting platform is such that the grippers are openedautomatically on the retract stroke, whereupon the blank previouslyplaced on the feeding platform causes the threaded nipple to bedischarged forwardly from the grippers while the grippers are movingwith the carriage over the new blank. During the entire cycle theoperator of the preferred embodiment of the machine need make but asimple motion of a single lever with one hand, and the other hand needonly place a nipple on the blank-receiving platform during the threadingoperation, which does not delay initiation of the threading operation.

In a machine made according to the present invention, after a new blankis gripped in the grippers, the carriage is moved forwardly and the endof the blank yieldably pressed into the threading dies. In theillustrated embodiment, this is done by the operator moving the carriageforward manually. As soon as the threading dies start on a particularblank, the threading operation proceeds automatically, so that a minimumamount of time is required for starting each blank, and the operation isindependent of the driv of the threading spindles. Thus the totalhandling time for loading each blank is reduced, the proportion of theloading time which necessarily intervenes between the end of onethreading operation and the beginning of the next is reduced, and thetime required for starting a threading operation after a blank has beenloaded is maintained at a minimum, so that in normal use both threadingdies are in threading operation ninety per cent of the time and theproduction is increased tremendously over the prior machines.

Since, in the present invention, the threaded nipple is automaticallyejected forwardly upon retraction of the carriage, a chute may beprovided to receive the ejected nipples and transfer them to the otherside of the machine convenient to the operator for loading the platformsuccessi ely threads bothv ends. of each blank.v

In addition to their complexity and expense, such machines do notapproach the high production of the present invention because thefeeding cams for the carriage are-geared in syn-- chronism with therotating threading dies, and in order to insure that the threading of'each blank is uniformly started, and that the blank will be completelythreaded before the controlling cams retract carriage, it is necessaryto time the dies to make a number of extra turns over that required tocarry out a normal threading operation.

Fur hermore. since the stroke of the ca riage of such machines isusually constant and is long enough to handle long nipples, when shortnipples' are threaded unnecessary tir e is consumed by traversal of thecarriage. With the machine of the present invention the carriagemovement is independent of the die rotation, and the position of thecarriage controls the opening and closing of the dies and grippers sothat adjustments are readily made to reduce carriage travel to theminimum reouiredfor a nipple of given length.

Another disadvantage of prior automatic machines resides in the factthat it may take many hours to change the setup and cam arrangements toconvert from one size nipple to another, whereas the machine of theinvention is converted as readily as is a hand machine.

With the novel combination of elements referred to in the foregoingbrief descri tion of applicants machine, it has been fo nd that with onedouble-bank machine controlled by a single operator, a productionschedule can be maintained which equals that provided by one oneratortending two of the complex and costly double-bank automatic machines.Yet, the machine of this invention retains all the flexibility,simplicity and ease of conversion to different nipple sizes that ischaracteristic of the slower type hand machines of the prior art.

It is another feature of a preferred embodiment of the invention thatmeans for controlling the opening and closing of the grippers inaccordance with carriage position are interconnected with theself-opening die head mechanism so that the grippers are opened as soonas the nipple end is clear out of the die, and remain open during theback stroke of the carriage. On the other hand, the grippers are closedat the end of the back stroke and remain closed during the forwardstroke so that there is no danger of the nipple changing its positionwith the grippers. This facilitates the rearward loading andself-ejecting operation previously referred to, in addition to providingfor positive carrying of the nipples.

Other improvements and advantages incident to the invention will appearin the following detailed description of a preferred embodiment thereof.

In the drawings, the machine elements that are conventional or wellknown to those skilled in the art are not illustrated in detail, itbeing understood that such elements as the self-opening die head arestandard articles of commerce in the art.

Fig. l is a rear end view of the machine made in accordance with theinvention with parts broken away;

Fig. 2 is a partial side view of #1 bank of the preferred embodiment ofthe invention;

Fig. 3; is a view similar to Fig. 2 with parts broken away in section;

Fig. 4' is afragmentary plan view of the machine;

Fig; 5. isan enlarged view of the carriage and grippers;

Figs. 6 to 9, inclusive, are schematic diagrams showing four steps inthe operation of the machine;v and,

Fig. 10 is a fragmentary side view showing a modified form.

Referring to Figs. 1 to 5 wherein a preferred embodiment of theinvention is illustrated, it should be understood that details of themeans for driving the die heads, die head construction and machinedesign elements known to this art are not illustrated in detail.

We have found that one operator can operate the doubleor two-bankmachine at the maximum production of each bank, and although theinvention is not limited tothe use of a two-bank machine, such is thepreferred form. Each bank of the machine includes several basicelements, all cooperating to attain the advantages previously referredto. These elements include the frame or bed structure it upon which aremounted the two banks A and B. For example, bank A includes a rotatableself-feeding and selfopening die head assembly D turned to the desiredthreading speed by motor and gearing not shown; a manually reciprocablecarriage C that is moved to and from the die head. under control of theoperator; blank grippersG-for carrying the blank to and from the diehead; and fluid motor means M for automatically opening and closing thegrippers. The. corresponding elements in bank B are lettered similarlywith a. subscript. "1 appended.

Die head mechanism The diehead D is of the type that is self-feedingoncethe blank is started therein by the operators' control of the carriage.As is well known in the art, the die head maybe of the type that isself-opening after the proper length of blank has been threaded. Onemeans of accomplishing this is by providing a shoulder or an abutmentmeans in the die head that is engaged by the blank when the threadingoperation is completed or substantially so. This trips mechanismv in thedie head and causes it to open so that the threaded blank can beretracted from the die head. by operation of the carriage,

Manual means are generally provided to open and. close the dies whichmay take the form of a lever H pivoted to a collar l in that operatesthe die trip mechanism, and pivoted to the machine frame as at. 52.. Inthe preferred form of the invention, lever i i has an extension 43disposed in a mid-section of the machine for facilitating automaticclosing of the dies when the carriage is retracted. Linkage foreffecting this includes a link l4 extending from the extension I3 of thedie head operatin lever. As best seen in Fig. 3, link 14 connects to adouble: crank arm l6- pivottoward the fixed one.

amen

ally mounted at I! on a support line l8, the latter being pivotallyfixed to the frame as at l9. This arrangement accommodates for theslightly vertical oscillation of the lower end of lever H.

In order to provide for automatic closing of the die when the carriageis retracted, we prefer to provide a shift rod 22 pivoted to the crankit as at 2|, and provide it with forward and rearward adjustable collars23 and 24 respectively. The arrangement is such that when the carriageis retracted after the die has been opened, the abutment means 31 on thecarriage is pulled against collar 24 which causes the die operatingmeans to operate the linkage just described, and close th dies jaws,these jaws being shown in their closed position in Figs. 2 and 3.

In the broader aspects of our invention, instead of relying uponabutment means integral with the die head for openin of the die inresponse to engagement of the blank being threaded, we could employequivalent structure by adjusting the collar 23 so that abutment means31a in the carriage causes the dies to snap open when the carriagereaches a predetermined position. In either event, it can be seen thatthe opening and closing of the die head is automatically determined bythe position of the carriage relative to the frame and die head.

Carriage Continuing with the detailed explanation of a preferredembodiment, the carriage assembly C includes a body section 30 andguides 3| for sliding on ways provided in the bed of the machine inaccordance with conventional machine design practice. To cause manualreciprocation of the carriage, a rock shaft 32 is mounted in thecarriage and keyed to a forked arm 33 which reacts against a pin 34fixed to the carriage in response to manual motion of thecarriage-operating lever 36.

Grippers As best seen in Fig. 5, the gripper assembly G mounted on thecarriage includes adjustablymounted, fixed jaw 40 and a movable jaw 68aslidably mounted in suitable guides 4!, there being adjusting means 42and 43 for positioning the fixed jaw 40 so that it is centered with re-"spect to the blank. Replaceable jaw members 44 are fastened by suitablemeans 46 and formed to grip the blank when the movable jaw is forced Inorder to cause reciprocation of the movable jaw 48a for gripping theblank, the fluid motor assembly M is provided. This includes 'a cylinder5! mounted on the carriage by any suitable means 52, the cylinder beingfitted with double acting piston 53.

A piston rod 54 is attached to the movable jaw member 40a by means ofsuitable bolt means 56.

Gripper control mechanism A carriage-mounted control assembly isprovided for causing actuation of the motor means M to open and closethe movable jaw or gripper 4011. Where a fluid motor, such as an air orhydraulic piston and cylinder assembly is employed,

this may take the form of a valve member 69 6 connections in the valveare reversed and fluid under pressure i admitted in front of the pistonto cause the gripper to open and release the blank. 7

As seen in Fig. 2, there is a cam follower device associated with thevalve and going to complete the carriage-mounted control assembly forthe motor M. This may take the form of a depending block 65 attached tosupport means 52, slotted as at 66, for reception of a cam followerbell-crank lever 61. This lever includes a cam follower roller 68 and anarm 69 for lifting the valve plunger 65. As best seen in Fig. 2, acarriage-mounted operator for the fluid motor control device isprovided. In the preferred form, an angle H may be fastened to the frameprovided with a rail 12. An adjustably mounted cam member includes abase 13 and a wear plate it, integral therewith that forms a cam surfacefor operatin the bell-crank lever 61 under certain conditions, to behereinafter described.

Mechanism is provided for connecting the operator cam with the die headoperating means previously described. This mechanism may take the formof a clevis Tl fastened to the cam 13, link 18 pivoted to the clevis andto a crank arm 19 keyed to the shaft l'l. Adjustable stop means 8! onblock 86 may be provided for limiting the motion of the cam in onedirection. Shaft I1 is turned when double crank arm I6 (shown in Fi s. 2and 3) is moved by shifting of the die operating lever ll. This causesrotation of the crank 19, and the position of the cam is changed. Whenthe lever l I is moved to close the threading jaws of the die, the cam13 is lowered as shown in Fig. 2, and the bell-crank lever 61 isdisposed so that plunger 64 is in its lowermost position. Theconnections to the fluid motor are now such that the grippers or jawsare closed. If the threading jaws of the die are opened, lever H ismoved so as to raise the cam. With the cam in its raised position, asthe carriage is retracted roller 58 rides upon the cam and plunger $4 islifted which adjusts the connections to the fluid motor and causes thegripper to open and release the blank, after the carriage has retracteda sufficient distance to withdraw the blank from the die head.

Loading and ejecting device A semi-automatic loading and blank ejectingmeans are provided and disposed rearwardly of the carriage. In thepreferred form, a V-shaped trough 82 is supported on the carriage by anyconvenient bracket means 83 and the terminal portion of the trough iscut away (as seen in Figs. 3 and 5) to clear the grippers in both theopen and closed position thereof. An adjustable stop or ejector means issupported on the frame by bracket 85, and may comprise a rod 86 slidablymounted in the bracket so that it is adjust- .able along the trough 82.A spring finger 81 may alsq beprovidglto directthe completely threadednipples frornbank B to any convenient receptacle.

Operation Theoperation of the. preferred embodiment just. described willnow be explained. Assume that the machine is being first put intooperation andis unloaded, but adjusted for the length of nipple to beproduced. This adjustment entails selecting the roper speed of rotationfor the die head; adjustment of the stop bar BBfor, the length of nippleand adjustment of collars 23 and 2d to causeproper opening and closingof the die head. Also, suitable-receptacles containing unthreaded blanksandblanksthreaded at one end are disposedadjacent machine banksA and 3-respectively. The operator standing-behind the machine placeshis righthand on levertfi ofbank A and moves thecarriage forward. With his lefthand. he. picksupan unthreaded nipple and lays it in trough 32; againstthe stop 88. Lever ii is pushed forward andtl e die head is opened,which lifts cam 'Mand causes the movable gripper 42a to open. Thecarriage and die head operating lever are set in the same manner for theother bank B; and the machine is ready for operation.

The nipple N is then laid in trough 82 against stop 88 and the carriageretracted. As this occurs, the grippers encompass the nipple and whenthe carriage reaches its rearward position, abutment means on thecarriage 3! strikes collar 2 to close the die head. Closing of the diehead operates the various linkages and causes the earn it to drop,whereupon plunger E54 controlling the valve 66 drops and the m vablegripper tta grips the blank.

With the machine set up for operation as described, the principles ofthe cycle may be readily understood by referring to Figs. 6 to 9. Asseen in Fig; 6, with the nipple N gripped by the gripper assembly G, theoperator advances the carriage with one'hand by means of lever 36 andurges the nippleinto proper engagement with the threading or-chasingdies '1, and with the carriage advanced lays a blank N1 on trough 82with the other hand. The threading dies pick up the blank and, beingself-feeding, thread it automatically.

During the threading operation, the operator transfers his attention tobank B and repeats the operations just described. The completion of thethreading operation in the first bank is illustrated diagrammatically inFig. 7 wherein the nippleN has engaged an abutment means 8 within thedie and causes the die jaws to open. This also lifts cam M into the pathof the cam follower, but has no effect on the grippers because the camfollower is forward of the cam.

When the operator perceives the opening of the die head in the firstbank, he merely grasps with one hand thelever 36 for that bank and withone continuous motion retracts the carriage. As seen in Fig. 8, early inthe retract stroke cam follower 6i rides up on the previously raised camand causes gripper 49a to open. As retraction continues, the grippersencompass the unthreaded blank N1 which ejects the threaded blank N, asseen in Fig. 9. At the end of the retract stroke, the new blank N1 is inplace between the grippers and the abutment means 31 engages its collarto close the dies. This lowers the cam causing the grippers to close.Without removing his hand fromthe lever 36 and without need forhesitation, thefoperator rapidly advances the carriage, (as seen inEig.6) toward the now closed die head 8 and loads thetroughbehindthecarriage with a third nipple.

These operations are then repeated on the second bank while the nippleN1 is being threaded in-the firstbank.

The total loading time is reducedto a minimum, since itisonly necessaryto retract and advancethe carriage and lay, a new blank on the troughv82, which ma be done while the carriage is being advanced. Theportionof, the loading time which necessarily intervenes bctween 'successive threading operations is only that time necessary to retract andadvance the carriage and yieldably press theblank gripped, into thecarriage intothe threading dies. Since thisoperation is independent of.the timing of the threading dies, the time required is reduced to theminimum so that both threading dies are actually'threading about ninetyperfcentof the time. Sincethe total loading time isfreduced, a furtherincrease in production isobt'ained on many sizes and types of nipples,particularly the smaller sizes, by increasing the cutting speed of thethreading dies. In prior machines working on such sizes and types of,nipples, it was useless to increase the threading speed to the maximumspeed at which threading can be accomplished, since the production waslimited by the handling and loading time, and any such increase merelyincreased the time during which the machine was waiting for theoperator.

For example, a particular prior art doublebank machine operating at onehundred per cent operating efiiciency on one-half inch spacenipp-les, atthe cuttingspeed recommended bythe manufacturer, thirty-three feet per.minute, is capable of producing but three hundred finished nipples perhour. A machine of the same size embodying the present invention,operating at the same threading speed on the same nipples, is capable ofproducing eight hundred sixtyeight and eight-tenths finished nipples perhour, an incr ase in production of about two hundred ninety per cent.The same machine is actually operated on the same nipples at a cuttingspeed of forty-one and three-tenths feet per minute, and at one hundredper cent operating efficiency is capable of producing one thousandeighty-six finished nipples per hour, an increase of three hundredsixty-two per cent, without any increase in operator skill or fatigue.Even greater. incr ases ar obtained in the smaller size nipples.

It will also be apparent that in the illustrated embodiment the loadingoperation involves a mere dropping of a blank on the loading. trough B2behind the carriage so that there is no danger of the operator injuringhis hands as exists in a. machine wherein the blank must be insertedbetween the grippers from the front which is adjacent to the rapidlyrotating die head.

Also, due to the fact that the movement of the carriage is independentof the rotation of the dies or other parts of the machinathe stroke ofcarriage travel may be made just long enough to accommodate the lengthof nipple being machined, which increases operating speed as nipplelength decreases.

Since the operation of the die head and grippers is controlled by theposition of the carriage, and the blank is yieldably pressed into thedies, no delay is required such as is required in prior automaticmachinery and the output of a single dual hand machinelike, that justdescribed equals the output of two of theprior automatic me chines.

assi n 9 Modified form Fig. 10 shows a modified form which embodiescertain elements of the invention, but forms a simplified construction.The arrangement of the carriage, jaws, jaw-operating means, andworksupporting and ejecting means is like that previously described inthe modified form, and details thereof will be omitted.

Frame III) mounts a pair of carriages, one of which, C2, is shown in theview. Each carriage has jaw-operating motor means, one motor M2 beingvisible, and a pair of die heads are provided, one of them D2 appearingin the drawing. Manu-al lever III may be provided for manipulating thedie head which may be of a self-closing type as described previously.The die head is also made self-opening, either with the linkag and levermeans previously described, or by means of a rod I22 (shown in thedrawing) that operates the die opening lever III and causes the dies toclose as the carriage reaches the rearward portion of its back stroke. Ahand control lever I36 is provided for each carriage and awork-supporting platform I82 and stop rod I86 are likewise provided. Thejaws are controlled by relative motion of the carriage and a fixed camI12. The control valve I60 for the motor has an operating pin I64 whichmay be lifted by the bell-crank lever I61 as it rides up on the cam "2.

From the standpoint of operation, the form shown in Fig. 10 is nodifferent from that previously described. The only major structuraldifference between the forms is that in the form shown in Fig. 10, thechuck jaws do not close as soon as the carriage has completed its backstroke, but remain open until the carriage is advanced to a positionwherein the cam follower leaves the cam. Thus, with this form relianceis had upon the pressure of spring such as 81, seen in Fig. 5, forretaining the blank in the jaws during the portion of the forward strokein which the jaws are open. However, the form shown in Fig. 10 has allthe advantages of ease and speed of operation together with safety ofthe previously described embodiment.

Although the foregoing description is necessarily of a detailedcharacter, in order that the invention may be completely set forth, itis to be understood that the specific terminology in the description isnot intended to be restrictive or confining, and that variousrearrangements of parts and modifications of detail may be resorted towithout departing from the scope or spirit of the invention as hereinclaimed.

What is claimed is:

l. A threading machine comprising in combination a frame, a rotatabledie head mounted on said frame, a carriage reciprocably mounted on saidframe, a control for moving said carriage toward and away from said diehead, non-rotatabl blank gripping means carried by said carriage, diehead operating means including means arranged to open the head whenengaged by means moving with the carriage at completion of threading andmeans to close the die head, when engaged by the carriage adjacent itsrearward position, motor means connected for opening and closing saidblank gripping means, a, carriage-mounted control device for said motormeans, an operator for moving said control device adjustably mounted onsaid frame and connected to said die head operating means, said die headoperating means and connections being arranged so that when the die headis open said operator is placed in one position for causing said controldevice to actuate 1O the motor means in order to open the blank grippingmeans, said die head operating means and connections being arranged sothat when the die head is closed said operator is placed in anotherposition for causing said control device to actuate the motor means inorder to close the gripping means, and blank support and fixed stopmeans disposed rearwardly of said blank gripping means, aid blanksupporting and gripping means being constructed and arranged to permitsaid gripping means, when open, to advance rearwardly over a supportedblank to eject the blank formerly disposed in the gripping means andpositions said gripping means over said supported blank.

2. A threading machine comprising in combination a frame, a rotatabledie head mounted on said frame, a carriage reciprocably mounted on saidframe and including abutment means, a control for moving said carriagetoward and away from said die head, blank gripping meanscarried by saidcarriage, die head operating means including means arranged to open thehead when engaged by a blank being threaded in the head after threadingand means to close the die head when engaged by said carriage abutmentmeans with the carriage adjacent its rearward position, fluid motormeans connected for opening and closing said blank gripping means, acarriage-mounted control valve for said fluid motor, a cam aajustablymounted on said frame and arranged to assume two positions, a camfollower movable with said carriage for operating said valve to open thegrippers when said cam is in one position and to close the grippers whensaid cam is in the other position, and a connection between said cam andsaid die head operating means, said die head operating means andconnection being arranged so that when the die head is open said cam isin said one position and when the die head is closed said cam is in saidother position.

3. A threading machine comprising in combination a frame, a rotatabledie head mounted on said frame, a carriage reciprocably mounted on saidframe and including abutment means, means associated with said carriagefor moving it toward and away from said die head, blank gripping meanscarried by said carriage, die head operating means including meansarranged to open the head when engaged by means moving with the carriageafter threading and means to close the die head when engaged by saidcarriage abutment means with the carriage adjacent its rearwardposition, fluid motor means connected for opening and closing said blankgripping means, a carriage-mounted control valve for said motor means, acam adjustably mounted on said frame and arranged to assume twopositions, a cam follower movable with said carriage for operating saidvalve to open the grippers when said cam is in one position and to closethe grippers when said cam is in the other position, and a connectionbetween said cam and said die head operating means, said die headoperating means and connection being arranged so that when the die headis open said cam is in said one position and when the die head is closedsaid cam is in said other position.

4, A threading machine comprising in combination a frame, a rotatabledie head mounted on said frame, a carriage reciprocably mounted on saidframe, a manually operable control for moving said carriage toward andaway from said die head, blank gripping means carried by said carriage,die head operatingme'ans'including means arrangedto open the head whenengaged by means moving withthe'carriage after threading and means toclose the die head when engaged by means moving with the carriageadjacent its rearward position, means moving in synchronism with saidcarriage for causing said die head operating means to close when thecarriage is adjacent its rearward position, fluid motor means-connectedfor opening and closing said blank gripping means, a carriagemountedcontrol valve for said motor means, a cam radjustably mounted on saidframe and arranged to assume two positions, a cam follower movable withsaid carriage for operating said valve to open the grippers when saidcam is in one position and to close the grippers when said cam is in theother position, and a connection between said cam and said die headoperating means, said die head operating means and connection beingarranged so thatwhen the die head is open said cam is in said oneposition and when the die head is closed said cam is in said otherposition.

5. A threading machine comprising in combination a frame, a rotatabledie head mounted on said frame, a carriage reciprocably mounted on saidframe, a manually operable control for moving said carriage toward andaway from said die head, blank gripping means carried by said carriage,a blank support and fixed stop means disposed rearwardly of saidcarriage, die head operating means including means arranged to open thehead when engaged by means moving with the carriage after threading andmeans to close the die head when engaged by means moving with thecarriage adjacent its rearward position, means moving in synchronismwith said carriage for causing said die head operating means to closewhen the carriage is adjacent its rearward position, fluid motor meansconnected for opening and closing said blank gripping means, acarriage-mounted control valve for said motor means, a cam adjustablymounted on said frame and arranged to assume two positions, a camfollower movable with said carriage for operating said valve to open thegrippers when said cam is in one position and to close the grippers whensaid cam is in the other position, and a connection between said cam andsaid die head operating means, said die head operating means andconnection being arranged 12 so that when the die head is open said camis in said one positionand when the die head is closed said cam is insaid other position.

I 6. A threading machine comprising incombination a frame, a rotatabledie head mounted on said frame, a carriage reciprocably mounted on saidframe, manually operable control pier moving said carriagetoward andaway from said die head, blank gripping means carried by said carriage,die head operating means arrangedto open the head when engaged by meansmoving with the carriage after threading, fluid;motor means connectedfor opening and closing said blank gripping means, a carriage-mountedcontrol valve for said motor means, a follower movable with saidcarriage for operating said valve, a cam mounted on said frame, said cambeing disposed in the path'of saidfollower for causing said controlvalve'to actuate the motor means in order to openthe blank grippingmeans as the carriage is retracted from the die head, means moving insynchronism with said carriage forcausing said die head operating meansto close when the carriage is adjacent its rearward position, blanksupport and fixed stop means disposed rearwardly of said blank grippingmeans, said blank support and gripping means being constructed andarranged to permit said gripping means, when open, to advance.rearwardly over a supported blank to eject the blank formerly disposedin the gripping means'and position said gripping means over saidsupported blank. H

IRVIN D. JACOBSON. RICHARD F. HERR.

' REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,457,603 Rankin June 5, 19231,740,495 'Briese et al .Dec. 24, 1929 2,067,626 Benninghoif Jan. 12',1937 2,360,906 7 Smith Oct. 24, 1944 2,389,556 7 Siegerist Nov. 20, 1945FOREIGN PATENTS Number Country Date 296,088 Great Britain Mar. 14, 1927

